CN110446862B

CN110446862B - Fastening member

Info

Publication number: CN110446862B
Application number: CN201880019289.8A
Authority: CN
Inventors: 金田教良; 铃木健
Original assignee: NHK Spring Co Ltd
Current assignee: NHK Spring Co Ltd
Priority date: 2017-03-24
Filing date: 2018-03-02
Publication date: 2022-02-01
Anticipated expiration: 2038-03-02
Also published as: US11286972B2; JP6815482B2; US20200072272A1; CN110446862A; JPWO2018173705A1; EP3604835A4; WO2018173705A1; EP3604835A1

Abstract

The fastening member of the present invention has a head portion and a shaft portion formed with a thread, the shaft portion having a main body portion and an outer peripheral portion provided radially outward of the main body portion, the outer peripheral portion of the thread being formed of a first alloy material and forming a portion including at least a crest portion of the thread, the main body portion of the thread being formed of a second alloy material having a higher tensile strength than the first alloy material and forming a portion including a root of the thread, the outer peripheral portion of the thread having a thick portion having a maximum wall thickness in a circumferential direction of the shaft portion and a thin portion having a minimum wall thickness in the circumferential direction of the shaft portion.

Description

Fastening member

Technical Field

The present invention relates to fastening components.

Background

In order to satisfy the demands for weight reduction of parts in the entire industrial field, weight reduction has been attempted from various viewpoints for fastening members such as bolts and screws and fastening structures using the same. On the other hand, it is necessary to improve both reliability and durability as a fastening member, and both of them should be compatible.

In view of the above problems, a technique of combining two kinds of alloys by a composite process or the like to be applied to a bolt has been gradually popularized. For example, patent document 1 describes a bolt made of an aluminum base material and having its surface covered with nickel.

Patent document 1: japanese laid-open patent publication No. 11-210728

Disclosure of Invention

However, although a bolt formed of a material in which two kinds of alloys are combined, such as a composite material including aluminum, can be reduced in weight, the bolt often has a problem in reliability and durability as a fastening structure. That is, looseness may occur after repeated use.

In view of the above problems, the present invention aims to: the fastening member is reduced in weight while reducing the occurrence of looseness, thereby improving reliability and durability as a fastening structure.

In order to solve the above problems, a fastening member of the present invention is a fastening member having a thread formed thereon, the fastening member including: the portion of the thread including the crest portion is made of a first alloy material, and has a thick portion having a maximum wall thickness in the circumferential direction and a thin portion having a minimum wall thickness, and the portion of the thread including the root portion is made of a second alloy material having a higher tensile strength than the first alloy material.

The fastening member of the present invention has a head portion and a shaft portion formed with a thread, and is characterized in that: the shaft portion has a main body portion and an outer peripheral portion provided radially outward of the main body portion, the outer peripheral portion of the thread is made of a first alloy material and forms a portion including at least a crest portion of the thread, the main body portion of the thread is made of a second alloy material having a higher tensile strength than the first alloy material and forms a portion including a root of the thread, and the outer peripheral portion of the thread has a thick portion having a largest wall thickness in a circumferential direction of the shaft portion and a thin portion having a smallest wall thickness in the circumferential direction of the shaft portion.

Other fastening members of the present invention are characterized in that: the outer peripheral portion is eccentric with respect to the body portion, thereby forming the thick portion and the thin portion.

Other fastening members of the present invention are characterized in that: the thick portion and the thin portion are located on opposite sides with respect to a central axis of the shaft portion.

Other fastening members of the present invention are characterized in that: the screw portion formed at the axial intermediate portion of the shaft portion has one or more screw threads formed therein, the screw threads being formed once around the axis of the shaft portion, and the screw portion has one thick portion and one thin portion formed at least once in the screw threads.

Other fastening members of the present invention are characterized in that: the first alloy material is an aluminum-based alloy of JIS Japanese industrial standard 1000 series or 6000 series, and the second alloy material is an aluminum-based alloy of JIS Japanese industrial standard 2000 series or 7000 series.

The fastening member of the present invention is formed with a thread, and is characterized in that: the thread has a main body portion and an inner peripheral portion provided radially inside the main body portion, wherein the inner peripheral portion of the thread is made of a first alloy material and forms a portion including at least a crest portion of the thread, the main body portion of the thread is made of a second alloy material having a higher tensile strength than the first alloy material and forms a portion including a root of the thread, and the inner peripheral portion of the thread has a thick portion having a largest wall thickness in a circumferential direction and a thin portion having a smallest wall thickness in the circumferential direction.

According to the present invention, a fastening member having excellent reliability and durability can be provided while achieving weight reduction of the fastening member.

Drawings

Fig. 1 is a side view showing the structure of a fastening member according to embodiment 1 of the present invention.

Fig. 2 is a cross-sectional view of the fastening member shown in fig. 1, including a central axis.

Fig. 3 is a schematic view of a section C-C of the fastening member shown in fig. 1.

Fig. 4 is an enlarged view of the area a in fig. 2.

Fig. 5 is an enlarged view of a region B in fig. 2.

Fig. 6 is an X-ray CT scan photograph of a cross section including the central axis of the bolt of example 1.

Fig. 7 is an X-ray CT scan photograph of a cross section including the central axis of the bolt of example 2.

Fig. 8 is the result of the socker vibration test of the bolts of example 1 and example 2.

Fig. 9 is an enlarged view of a cross section including a center axis of the fastening member according to embodiment 2 of the present invention.

Fig. 10 is another enlarged view of a cross section including a center axis of the fastening member according to embodiment 2 of the present invention.

Fig. 11 is a plan view showing the structure of a fastening member according to embodiment 3 of the present invention.

Fig. 12 is a cross-sectional view taken along line D-D of fig. 11.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment mode 1

Fig. 1 is a side view showing a fastening member 1 according to embodiment 1 of the present invention. The fastening member 1 is a bolt (a type of male screw member), and has a hexagonal head portion 3 and a rod-shaped shaft portion 2. A threaded portion 22 is provided at an axially (extending direction) intermediate portion of the shaft portion 2, and a plurality of screw threads 21 are formed. The thread 21 is once wound around the axis of the shaft portion 2, and both ends thereof are offset in the axial direction. In each of the screw threads 21, the screw threads 21 adjacent in the axial direction are connected to each other. The plurality of screw threads 21 in the screw portion 22 extend spirally. The shape of the head 3 is not limited to the hexagonal shape, and may be a flat head type, a cylindrical head type, or other shapes.

Fig. 2 is a sectional view of the fastening member 1 including the axial center axis of the shaft portion 2. The shaft portion 2 has a main body portion 12 and an outer peripheral portion 14, the main body portion 12 being an inner peripheral portion, the outer peripheral portion 14 constituting an outer peripheral portion of the shaft portion 2 (radially outer side of the main body portion 12). The outer peripheral portion 14 and the main body portion 12 are made of a first alloy material 1a and a second alloy material 1b, which are two different alloys. The first alloy material 1a constitutes an outer peripheral portion 14 on the radially outer side of the main body portion 12. The second alloy material 1b constitutes the main body 12 which is the inner peripheral portion of the shaft portion 2. The second alloy material 1b has a higher strength, particularly a higher tensile strength, than the first alloy material 1a constituting the outer peripheral portion 14, because it constitutes the main body portion 12.

As the material of the shaft portion 2, a composite material of the first alloy material 1a and the second alloy material 1b can be used.

As the first alloy material 1a and the second alloy material 1b, two alloys containing the same element as a main component can be used. For example, two aluminum-based alloys may be used.

As the

first alloy material

1a, 1000 series or 6000 series aluminum-based alloy may be used. For example, as the first alloy material 1a, JIS standard (japanese industrial standard) a6063 may be used. Further, JIS standard a6056 may also be used. These aluminum-based alloys are relatively lightweight alloys having high strength and excellent corrosion resistance and stress corrosion resistance.

As the

second alloy material

1b, 2000 series or 7000 series aluminum-based alloy may be used. For example, JIS standards a2618 and a2024 may be used as the second alloy material 1 b. It is a high strength aluminum-based alloy having high tensile strength and relatively light weight. In particular, it has a higher tensile strength than the aluminum-based alloy as the first alloy material 1 a.

Further, as the first alloy material 1a and the second alloy material 1b, two kinds of alloys containing different elements as main components may be used.

A main body 12 is present on the inner peripheral side of the shaft 2, and an outer peripheral portion 14 covers the outer peripheral portion thereof. The outer peripheral portion 14 does not need to completely cover the body portion 12, and may be exposed to a part of the head portion 3 and an end portion of the shaft portion 2 on the opposite side of the head portion 3, as shown in fig. 2, for example.

Fig. 3 is a schematic view of a C-C section of the fastening member 1 (a central axial sectional view of the shaft portion 2). As shown in fig. 3, the thickness of the outer peripheral portion 14 varies depending on the position in the circumferential direction of the shaft portion 2. The outer peripheral portion 14 has a maximum thickness portion and a minimum thickness portion in a region located on the opposite side (a portion on the opposite side of approximately 180 degrees) of the maximum thickness portion with respect to the central axis of the shaft portion 2. That is, the outer peripheral portion 14 forms an outer peripheral portion of the main body 12 in a state of being eccentric radially outward with respect to the main body 12.

Here, "the outer peripheral portion 14 is eccentric with respect to the main body portion 12" means a state in which: when viewed in a cross-sectional view of the shaft portion 2 in the central axial direction, the positions of the virtual central axis of the outer peripheral portion 14 and the same virtual central axis of the body portion 12 are offset from each other and do not coincide with each other.

Fig. 4 is an enlarged view of a region a (maximum wall thickness portion) in fig. 2. As shown in fig. 4, at least the crest portion 21a of the thread 21 of the screw portion 22 is constituted by the outer peripheral portion 14. That is, the crest 21a of the thread 21 is made of the first alloy material 1 a. The wall thickness of the first alloy material 1a in the maximum wall thickness portion is the maximum wall thickness T1 at least at the thread ridge 21 including the ridge top 21 a.

The root side of the thread 21 is constituted by the main body 12. That is, the root side of the thread 21 is made of the second alloy material 1 b. The root portion 21b of the screw portion 22 is thinly covered with the outer peripheral portion 14, and the main body portion 12 is not exposed. That is, the root portion 21b is made of the first alloy material 1a as the outer peripheral portion 14.

Fig. 5 is an enlarged view of a region B (minimum wall thickness portion) in fig. 2. The minimum thickness portion is formed on the opposite side (a portion on the opposite side of approximately 180 degrees) of the maximum thickness portion with respect to the central axis of the shaft portion 2 in the same thread 21. As shown in fig. 5, at least the crest portion 21a of the screw thread 21 located at the minimum thickness portion is constituted by the outer peripheral portion 14. That is, the crest 21a of the thread 21 of this portion is made of the first alloy material 1 a. The wall thickness of the first alloy material 1a at the minimum wall thickness portion is, at least in the thread ridge 21 including the ridge top 21a, the minimum wall thickness T2(< T1).

As described above, in the threaded portion 22 of the fastening member 1, the outer peripheral portion 14 made of the first alloy material 1a has the maximum wall thickness T1 and the minimum wall thickness T2 in one thread 21. That is, the outer peripheral portion 14 made of the first alloy material 1a has a thick portion 23 and a thin portion 24 that are eccentric outward in the radial direction with respect to the main body portion 12 in one screw thread 21.

The maximum wall thickness portion (thick portion 23) and the minimum wall thickness portion (thin portion 24) of the outer peripheral portion 14 are not limited to one, and may be provided at a plurality of places in one thread 21. The maximum thickness portion (thick portion 23) and the minimum thickness portion (thin portion 24) of the outer peripheral portion 14 may be provided not only on all the screw threads 21 of the screw portion 22 but also on only some of the screw threads 21. Further, the maximum wall thickness portion (thick portion 23) and the minimum wall thickness portion (thin portion 24) of the outer peripheral portion 14 may not be located on opposite sides of 180 degrees from each other.

The operation and effect of the fastening member 1 according to embodiment 1 of the present invention will be described. When the fastening member 1 is fastened to the counterpart member, the thread 21 of the screw portion 22 is coupled to the counterpart member and fastened. At this time, the thick portion 23 occupies a larger portion of the first alloy material 1a than the other outer peripheral portions, and the thin portion 24 occupies a smaller portion of the first alloy material 1a than the other outer peripheral portions. That is, two materials having different strengths are present in the thick portion 23 and the thin portion 24 with their composition ratios changed. As a result, the axial load (load capacity) is unevenly distributed in the thick portion 23 and the thin portion 24, and the oblique load acts on the central axis of the shaft portion 2, so that the thick portion and the thin portion are firmly coupled to each other, and effective locking can be achieved.

Further, in the shaft portion 2 of the fastening member 1, since the outer peripheral portion 14 is made of the first alloy material 1a and the main body portion 12 is made of the second alloy material 1b, the material used in the entire fastening member can be optimized in accordance with the required strength and characteristics, and weight reduction can be achieved.

Further, since the thick portion 23 and the thin portion 24 are formed by making the outer peripheral portion 14 eccentric with respect to the central axis of the shaft portion 2, the fastening member 1 can be manufactured more easily.

Further, since the thick portion 23 and the thin portion 24 are located in the region on the opposite side (the portion on the opposite side of approximately 180 degrees) from the central axis of the shaft portion 2, an oblique load can be effectively generated with respect to the central axis, and a stronger fastening connection can be realized.

Further, since the 1000-series or 6000-series aluminum-based alloy, which is the first alloy material 1a constituting the outer peripheral portion 14, is excellent in corrosion resistance and stress corrosion resistance, the reliability as a fastening member can be further improved by covering the shaft portion 2 including the thread 21 with these materials. In addition, the aluminum-based alloy is lightweight, and therefore, the fastening member 1 can be further lightened.

Next, a specific configuration example of the fastening member 1 will be described. As specific configuration examples, the following examples 1 and 2 and conventional examples were prepared.

Example 1

The fastening member 1 (bolt) of the present embodiment is produced as follows: the rod-shaped composite material in which the main body portion 12 of the shaft portion 2 is covered at its outer peripheral portion with JIS a2618 and JIS a6063 is subjected to a cold heading step and a heat treatment step, and then the threaded portion 22 is formed by a thread rolling step. The bolt size was M8 × 50.

Fig. 6 is an X-ray CT scan photograph of a cross section including the central axis of the bolt of example 1. The thickness of the outer peripheral portion 14 of the partial thread 21 formed in JIS a6063 was 607 μm, and the thickness of the outer peripheral portion 14 on the opposite side to the central axis was 680 μm.

Example 2

The fastening member 1 (bolt) of the present example was produced in the same manner as in example 1, except that the thickness of the outer peripheral portion of the composite material was changed.

Fig. 7 is an X-ray CT scan photograph of a cross section including the central axis of the bolt of example 2. The thickness of the outer peripheral portion 14 of the partial thread 21 formed of a6063 was 370 μm, and the thickness of the outer peripheral portion 14 on the opposite side to the center axis was 318 μm.

Description of the Prior Art

A fastening member (bolt) of the conventional example was produced in the same manner as in example 1, except that the shaft portion 2 and the head portion 3 were formed using only JIS a2618 material.

Fig. 8 shows the results of the socker vibration test of the bolts of example 1 and example 2. The Pockey vibration test is performed according to the fastener looseness resistant vibration test standard DIN 25201-4. As is apparent from fig. 8, the bolts according to examples 1 and 2 maintain a higher axial force even if the number of times of load vibration increases, as compared with the bolts according to the conventional examples. It is also understood that the axial force of the bolt of the conventional example gradually decreases as the number of times of vibration under load increases, whereas the bolts of examples 1 and 2 can maintain a constant axial force. Thus, the bolts of example 1 and example 2 exhibit high reliability as the fastening member 1.

Embodiment mode 2

Next, the fastening member of embodiment 2 will be explained. Here, the same reference numerals are given to parts of the components common to the fastening member 1 of embodiment 1, and the description thereof is omitted. As shown in fig. 9 and 10, the outer periphery of the body portion 12 has a convex shape corresponding to the screw thread 21. While the root side of the outer peripheral portion 14 has a concave shape corresponding to the convex shape of the outer periphery of the main body portion 12. That is, a part of the outer periphery of the main body portion 12 enters the inside of the thread 21.

Fig. 9 is an enlarged view of the maximum wall thickness portion. As shown in fig. 9, at least the crest portion 21a of the thread 21 of the screw portion 22 is constituted by the outer peripheral portion 14. That is, the crest portion 21a of the thread 21 is made of the first alloy material 1 a. The wall thickness of the first alloy material 1a at the maximum wall thickness portion is, at least at the thread ridge 21 including the crest 21a thereof, the maximum wall thickness T3. Here, the thickness of the first alloy material 1a according to embodiment 2 is a distance between the crest of the convex shape of the body 12 and the crest of the thread 21.

The root side of the thread 21 is constituted by the main body 12. That is, since the thread 21 has a convex portion on the outer periphery of the main body, a part thereof is made of the second alloy material 1b, and the other part is made of the first alloy material 1 a. The root portion 21b of the screw portion 22 is also constituted by the outer peripheral portion 14, and the main body portion 12 is not exposed. That is, the root portion 21b is made of the first alloy material 1 a.

Fig. 10 is an enlarged view of a portion of minimum wall thickness. The minimum thickness portion is formed on the opposite side (a portion on the opposite side of approximately 180 degrees) of the maximum thickness portion with respect to the central axis of the shaft portion 2 in the same thread 21. As shown in fig. 10, at least a crest portion 21a of the screw thread 21 at the minimum thickness portion is constituted by the outer peripheral portion 14. That is, the crest portion 21a of the thread 21 of this portion is made of the first alloy material 1 a. Further, the outer periphery of the body portion 12 enters further inside the thread 21, and the height of the convex shape of the outer periphery of the body portion 12 is higher than the maximum thickness portion. Therefore, the wall thickness of the first alloy material 1a of the minimum wall thickness portion, at least at the thread ridge 21 including the crest portion 21a thereof, is the minimum wall thickness T4(< T3).

The root side of the thread 21 is constituted by the main body 12. The root side of the thread 21 is made of the second alloy material 1 b. The root portion 21b of the screw portion 22 is also constituted by the outer peripheral portion 14, and the main body portion 12 is not exposed. That is, the root portion 21b is made of the first alloy material 1 a.

As described above, in the threaded portion 22 of the fastening member 1, the outer peripheral portion 14 made of the first alloy material 1a has the maximum wall thickness T3 and the minimum wall thickness T4 in one thread 21. That is, the outer peripheral portion 14 made of the first alloy material 1a has a thick portion 23 and a thin portion 24 that are eccentric outward in the radial direction with respect to the main body portion 12 in one thread 21.

The maximum thickness portion (thick portion 23) of the outer peripheral portion 14 is not limited to one point, and a plurality of points may be provided in one screw thread 21. The maximum thickness portion (thick portion 23) and the minimum thickness portion (thin portion 24) of the outer peripheral portion 14 may be provided not only on all the screw threads 21 of the screw portion 22 but also on only some of the screw threads 21.

Embodiment 3

Next, a fastening member according to embodiment 3 will be described. Here, the same reference numerals are given to portions common to the fastening member 1 of embodiment 1 or embodiment 2, and the description thereof is omitted. Fig. 11 is a plan view showing the structure of a fastening member according to embodiment 3 of the present invention. Fig. 12 is a cross-sectional view taken along line D-D of fig. 11. The fastening member 101 is a nut (a type of female screw member) having a hollow cylindrical shape, and has a screw thread 201 formed on an inner surface of a hole formed in a central portion thereof. The fastening member 101 has a threaded portion 202 formed on the inner peripheral surface thereof, and a plurality of threads 201 formed thereon. The shape of the fastening member 101 is not limited to the hexagonal nut shape, and may be other shapes such as a flange nut and a cap nut.

The fastening member 101 is composed of two alloys different from each other, i.e., a first alloy material 11a and a second alloy material 11 b. The first alloy material 11a constitutes an inner peripheral portion 104 that covers the surface of the thread ridge 201. The second alloy material 11b constitutes a main body portion 102, which is an outer peripheral portion of the fastening member. For example, the first alloy material 11a is the same material as the first alloy material 1a, and the second alloy material 11b is the same material as the second alloy material 1 b.

On the outer peripheral side of the fastening member 101, there is a body portion 102, and the inner surface of a hole formed in the central portion thereof is covered with an inner peripheral portion 104. The crest portion 201a and the root portion 201b of the threaded portion 202 are covered by the inner peripheral portion 104, and the main body portion 102 (the second alloy material 11b) is not exposed. The inner peripheral portion 104 does not need to completely cover the main body portion 102.

The thickness of the inner peripheral portion 104 (first alloy material 11a) differs depending on the circumferential position of the hole formed in the central portion. The inner peripheral portion 104 has a maximum thickness portion (thick portion 203) and a minimum thickness portion (thin portion 204) in a region on the opposite side (approximately 180 degrees opposite portion) of the central axis of the hole formed in the central portion, in the same thread 201 including the crest portion 21a of the thread 201. That is, the inner peripheral portion 104 covers the surface of the body portion 102 in a state in which a part of the circumferential direction thereof is eccentric radially inward with respect to the body portion 102.

The embodiments for carrying out the present invention have been described above, but the present invention is not limited to these embodiments, and can be carried out in various ways without departing from the scope of the present invention. For example, the fastening member may be a male screw other than a bolt, i.e., a screw or a tapping screw.

As described above, the present invention may include various embodiments and the like not described herein, and various design changes and the like may be made without departing from the scope of the technical idea defined by the claims.

As described above, the fastening member according to the present invention can reduce the weight of the fastening member and reduce the occurrence of looseness, and is suitable for improving the reliability and durability of the fastening structure.

Description of the symbols

1. 101 fastening part

1a, 11a first alloy material

1b, 11b second alloy material

12. 102 main body part

14 outer peripheral portion

104 inner peripheral portion

2 shaft part

3 head part

21. 201 thread

21a, 201a crest

21b, 201b root

22. 202 thread part

23. 203 thick part

24. 204 thin wall part

Claims

1. A fastening member having a head portion and a shaft portion formed with a thread, characterized in that:

the shaft portion has a main body portion and an outer peripheral portion that completely covers an outer peripheral portion of the shaft portion of the main body portion except for an end portion of the shaft portion,

the outer peripheral portion of the thread ridge is made of a first alloy material and forms a portion including at least a crest portion of the thread ridge,

the main body portion in the thread ridge being composed of a second alloy material having a higher tensile strength than the first alloy material, and forming a portion including a root of the thread ridge,

the outer peripheral portion of the thread has a thick portion that is eccentric with respect to the main body portion and has a largest wall thickness in the circumferential direction of the shaft portion, and a thin portion that has a smallest wall thickness in the circumferential direction of the shaft portion.

2. The fastening component of claim 1, wherein:

the thick portion and the thin portion are located on opposite sides with respect to a central axis of the shaft portion.

3. The fastening component of claim 1, wherein:

at least one screw thread is formed on a screw portion formed at an axially intermediate portion of the shaft portion,

the thread ridge is rotated once around the axis of the shaft portion,

in the thread portion, one of the thick-walled portions and one of the thin-walled portions are formed in at least one turn of the thread ridge.

4. The fastening component of claim 2, wherein:

the thread ridge is rotated once around the axis of the shaft portion,

5. The fastening member according to any one of claims 1 to 4, characterized in that:

the first alloy material is an aluminum-based alloy of JIS Japanese industrial standard 1000 series or 6000 series, and the second alloy material is an aluminum-based alloy of JIS Japanese industrial standard 2000 series or 7000 series.

6. A fastening member formed with a thread ridge, characterized in that:

having a main body portion and an inner peripheral portion completely covering an inner peripheral portion of the main body portion except for an end portion,

the inner peripheral portion of the thread ridge is made of a first alloy material and forms a portion including at least a crest portion of the thread ridge,

the inner peripheral portion of the thread has a thick portion that is eccentric with respect to the main body portion and has a largest wall thickness in the circumferential direction, and a thin portion that has a smallest wall thickness in the circumferential direction.